An internal hallucination is defined as the perception of a visual hallucination that exclusively occurs within an imagined environment which can typically only be viewed with closed eyes,[1][2] similar to those found within dreams.[3][4][5] This is in stark contrast to external hallucinations, which display themselves seamlessly into the external environment as if they were actually happening.

At lower levels, internal hallucinations begin with imagery on the back of a person's eyelids which do not take up the entirety of one's visual field and are distinct from their background. These can be described as spontaneous moving or still images of scenes, concepts, places, and anything one could imagine. The imagery is manifested in varying levels of realism, ranging from ill-defined and cartoon-like in nature to wholly realistic. They rarely hold their form for more than a few seconds before fading or shifting into another image. It is worth noting that this level of intensity occurs in a highly similar manner to that of hypnagogia, the state between sleep and wakefulness.

At higher levels, internal hallucinations become increasingly elaborate as they eventually become all-encompassing, fully-fledged 3D scenes which surround the person in a similar manner to that of dreams. This can create the feeling that one has "broken-through" into another reality. The things which occur within this perceived alternate reality can be anything but fall under common archetypes, such as contact with autonomous entities alongside a wide variety of imagined landscapes, and scenarios.

This effect is capable of manifesting itself across the 5 different levels of intensity described below:

Enhancement of mental visualization - At the lowest level internal hallucinations can be defined as a distinct enhancement of mental visualisation that a person drifts into when daydreaming or using their imagination. It can be described as a short-term detachment from one's immediate surroundings, during which a person's contact with reality is blurred and partially substituted by an ill-defined fantasy. The details of this internal visualisation are slightly spontaneous or autonomous in nature but are mostly controlled by the content of one's current thought stream.

Fully defined imagery - At this level, the vividness and intensity increases in a fashion which renders the imagery seen within one's visual field as fully defined and realistic in its appearance.

Partially defined immersion - At this level, the vividness, scope, and intensity of the hallucinations become all-encompassing in a way which begins to display momentary flashes of scenes which surround the person in an immersive environment in a similar fashion to that of a vague dream. Although all-encompassing, they are often blurred or transparent in appearance, and a person's physical body still feels as if it is partially connected to the real world.

Fully defined immersion - At the highest level, the internal hallucinations further increase to become all-encompassing in a manner which displays long-lasting scenes which surround the person with an explorable and fully immersive environment which is similar to that of a dream. This occurs in a fashion which is entirely realistic, detailed, and highly vivid in its appearance. It typically also occurs alongside relevant auditory and tactile hallucinations, as well as the sensation that a person has become completely disconnected from their physical body.

The content within these external hallucinations can be further broken down into four distinct subcomponents. These are described and documented within their own dedicated articles, each of which are listed below:

It is worth noting that the content, style, and general behaviour of an internal hallucination is often largely dependent on the emotional state of the person experiencing it. For example, a person who is emotionally stable and generally happy will usually be more prone to experiencing neutral, interesting, or positive hallucinations. In contrast, however, a person who is emotionally unstable and generally unhappy will usually be more prone to experiencing sinister, fear-inducing, and negative hallucinations.

Contents

Transition styles

Internal hallucinations typically last anywhere between 30 seconds and several minutes before the person slips back into reality or the presence of another hallucination. There are several different methods through which these hallucinations are transitioned between, these are described and documented below:

Zooming - Images can switch between each other via the experience of one's vision zooming into or out of the current image to such an extent that it reveals an entirely new hallucination.

Morphing - Images can switch between each other by transforming the details of their shape and structure to show an entirely new image. This can happen in a variety of different speeds and typically occurs in the style of a fluidlike motion.

Sliding - Images can switch between each other by sliding in a specific direction which then reveals an entirely new image behind them.

Fading - Images can change between each other by fading into nothingness before a completely new image fades back into view.

Splitting - Images can switch between each other by splitting into two or more sections which drift away from each other to reveal an entirely new hallucination behind it.

Tiling - Images can switch between each other by separating into geometric formations which then slide or fade away from each other to reveal an entirely new hallucination behind them.

Variations

The specific differences between each potential style of internal hallucination can be broken down into the following variations:

Lucid vs. Delirious - Hallucinatory states can maintain a consistent level of awareness throughout them regarding the fact that none of these events are actually happening and that the current situation is simply a result of drug-induced hallucination. In contrast to this, hallucinations can also become completely believable, no matter how nonsensical they may be, in the same way, that one does not have any problem accepting "absurd" and non-linear plots within ones dreams.

Interactive vs. Fixed – Hallucinatory states can either present themselves as completely separate in a manner, that is similar to watching a video play out in front of one's field of vision, or they can be completely interactive. For example, conversing with autonomous entities or interacting with imagined objects in a fashion similar to lucid dreaming is entirely possible.

New experiences vs. Memory replays – Regarding their subject matter, hallucinations can either be entirely new experiences or they can follow themes of normal, everyday situations and a replaying of specific memories.

Controllable vs. Autonomous – Imagery and hallucinations can be partially to completely controllable. This can be described as the content of their appearance always seeming to perfectly follow and fit the general topic and subject matter of one's current thought stream, with varying levels of partial to absolute control. In contrast, autonomous hallucinations are completely spontaneous in their subject matter and entirely uncontrollable.

Geometry-based vs. Solid – Hallucinations can be comprised of condensed psychedelicgeometry or they can appear to be made from realistic materials.